CN101413110A - Preparation of 1.3 micron waveband InAs quantum dot material - Google Patents

Abstract

The preparation method of InAs quantum dot material in 1.3 micron band is a method for preparing InAs/GaAs quantum dot material with luminescence wavelength in 1.3 micron band by using MOCVD technology, and belongs to the technical field of semiconductor material manufacturing. There is still a long way to go for practical and commercialization of known technologies using MBE epitaxy. The present invention adopts MOCVD epitaxial technology to grow each epitaxial layer; the InAs quantum dot layer is grown in two steps, the first step, the growth temperature is a temperature within the range of 470-490°C, and the growth thickness is 2.0-3.0ML, the second step and the second step Steps are separated by 20-60s in time, and the growth temperature is raised to 490-510°C within this time interval, and then continue to grow at a temperature within this temperature range, and the growth thickness is 0.5-1.5ML. A 1.3-micron band InAs quantum dot material capable of making devices with room temperature continuous working mode is prepared, the method is easy to control and the process is stable.

Description

Preparation method of InAs quantum dot material in 1.3 micron band

technical field

The invention relates to a method for preparing an InAs/GaAs quantum dot material with a light emission wavelength of 1.3 microns by using MOCVD (metal organic chemical vapor deposition) technology, and belongs to the technical field of semiconductor material manufacturing.

Background technique

The quantum dot material with the quantum dot structure as the active region has the advantages of lower threshold current density, higher optical gain, higher characteristic temperature and wider modulation bandwidth in theory, and has the advantages of manufacturing semiconductor lasers in Therefore, the field of quantum dot materials is an active field of invention.

In(Ga)As/GaAs quantum dot system has become a substitute for InP-based materials due to its unique and excellent photoelectric properties, and can be used to prepare 1.3μm band long-wavelength laser materials for optical communications. Since the GaAs substrate is cheaper than the InP substrate, AlGaAs can also be used as the confinement layer and waveguide layer, which can confine the carriers in the active region more strongly, and can be easily integrated with the existing GaAs microelectronics process technology. Together, therefore GaAs-based materials are gradually replacing InP-based materials.

It is a major technical problem to realize the continuous operation mode at room temperature for devices made of quantum dot materials. Improving the optical gain of quantum dot materials is an important technical approach to solve this technical problem, and this parameter is determined by the size uniformity and surface density of quantum dots in the material. On the premise of obtaining long-wavelength luminescence in the 1.3 μm band, it is technically difficult to improve the size uniformity and surface density from the perspective of preparation methods. That is to say, during the epitaxy process of the quantum dot layer, the quantum dots are aggregated and combined, the size of the quantum dots increases, and the emission wavelength moves to the long-wavelength direction until the long-wavelength light in the 1.3 μm band can be emitted. However, due to the aggregation and combination of quantum dots It will inevitably lead to a decrease in the density of quantum dots; in addition, the aggregation and bonding are not performed uniformly as desired, resulting in a decrease in the uniformity of quantum dot size. In view of this, a document number is that the patent literature of CN1786107A discloses a technical scheme, and this scheme adopts MBE (molecular beam epitaxy) technology to prepare In(Ga)As/GaAs quantum dot system material, and the epitaxy process of its quantum dot layer is In this way, the thickness of the grown InAs reaches 0.1ML (monatomic layer, the same below), pause for 5 seconds, and then repeat this process successively. This process is carried out 25 times in total, and an InAs quantum with a total thickness of 2.5ML is grown. point layer. The effect of this method is that in the process of growing the quantum dot layer, the quantum dots are supplemented intermittently, one increases the surface density of the quantum dots, reaching 4×10 ¹⁰ ; This improves. Wherein, the In _x Ga _1-x As strained buffer layer x=0.15.

MOCVD (Metal Organic Chemical Vapor Deposition) technology is also a commonly used epitaxial technology in the field of semiconductor material manufacturing. Compared with MBE, MOCVD is more suitable for industrial production.

Contents of the invention

The known technology can prepare In(Ga)As/GaAs quantum dot system materials in the 1.3 micron band that meet the requirements. However, due to the epitaxy technology used, there is still a distance from practical and commercialization as an intermediate product. In addition, in addition to the continuous operation mode at room temperature, the commercialization of the device also requires the required luminous intensity. In order to meet the needs of practicality and commercialization, we have proposed a technical solution called the preparation method of InAs quantum dot materials in the 1.3 micron band.

The present invention is realized by adopting MOCVD epitaxial technology to grow each epitaxial layer; the preparation steps include: sequentially growing a GaAs transition layer, an InAs quantum dot layer, an _{InxGa1 -xAs} strain layer, and a GaAs barrier layer on a GaAs substrate , GaAs covering layer; InAs quantum dot layer is grown in two steps, the first step, the growth temperature is a temperature in the range of 470 ~ 490 ° C, the growth thickness is 2.0 ~ 3.0ML, the second step is separated from the first step in time 20-60s, within this time interval, increase the growth temperature to 490-510°C, and then continue to grow at a temperature within this temperature range, with a growth thickness of 0.5-1.5ML.

The technical effect of the present invention is that MOCVD technology is used to prepare the 1.3 micron band InAs quantum dot material capable of making devices with room temperature continuous operation mode, which has good quantum dot size uniformity, as shown in Figure 1, which shows 1× The atomic force micrograph of the 1μm ² quantum dot surface shows that the quantum dot surface density is about 4×10 ¹⁰ , while the quantum dot surface density of the InAs quantum dot layer grown by one-step epitaxial growth is only 3×10 ¹⁰ . The peak wavelength is in the 1.3 micron band, and the half-peak width is 35meV, as shown in Figure 2. Moreover, the method of the invention is easy to control and the process is stable.

Description of drawings

Fig. 1 is the atomic force microscope (AFM) picture of the quantum dot surface of InAs quantum dot material of 1.3 micron band prepared by the method of the present invention. Fig. 2 is the photofluorescence spectrum diagram at room temperature of the 1.3 micron band InAs quantum dot material prepared by the method of the present invention, and this figure is also used as a summary drawing. Fig. 3 is a high-resolution scanning electron microscope (SEM) image of a quintet array quantum dot material.

Detailed ways

The present invention is achieved by adopting MOCVD epitaxial technology to grow each epitaxial layer, and adopting low-toxicity Group V organic source-tert-butyl arsenic (TBA) as the arsenic source, because it has higher cracking efficiency, thereby can improve quantum dot material optical gain. Preparation steps include:

Step 1: growing a GaAs transition layer on the GaAs substrate, the growth temperature is a temperature in the range of 650-700°C, and the growth thickness is 200nm;

Step 2: grow the InAs quantum dot layer on the GaAs transition layer, and grow it in two steps. In the first step, the growth temperature is a temperature in the range of 470-490°C, and the growth thickness is 2.0-3.0ML. The second step is the same as the first step. The steps are separated by 20-60s in time, and the growth temperature is increased to 490-510°C within this time interval, and then continue to grow at a temperature within this temperature range, and the growth thickness is 0.5-1.5ML;

Step 3: growing an In _x Ga _1-x As strained layer on the InAs quantum dot layer, 0.05≤x≤0.20, the growth temperature is a temperature in the range of 490-510°C, and the growth thickness is 5-10nm;

Step 4: growing a GaAs barrier layer on the In _x Ga _1-x As strained layer, the growth temperature is a temperature in the range of 490-510° C., and the growth thickness is 5-10 nm;

Step 5: growing a GaAs capping layer on the GaAs barrier layer, the growth temperature is a temperature in the range of 580-620° C., and the growth thickness is 30-50 nm.

In order to improve the luminous intensity of the prepared quantum dot material, it is necessary to take array measures, the specific method is as follows:

Step 6: Repeat steps 2 to 5 on the GaAs capping layer to obtain a double-array quantum dot material, and repeat it up to 14 times to obtain a fifteen-fold array quantum dot material.

The following example further illustrates the method of the present invention:

Embodiment 1: Each epitaxial layer is grown by MOCVD epitaxial technology, and a low-toxic Group V organic source-tert-butylarsenic (TBA) is used as the arsenic source. The preparation steps include:

Step 1: growing a GaAs transition layer on a GaAs substrate, the growth temperature is 700°C, and the growth thickness is 200nm;

Step 2: grow the InAs quantum dot layer on the GaAs transition layer in two steps. In the first step, the growth temperature is 480°C and the growth thickness is 2.4ML. The time interval between the second step and the first step is 30s. Increase the growth temperature to 500°C within a time interval, and then continue to grow at this temperature, with a growth thickness of 0.6ML;

Step 3: growing an _{InxGa1 -xAs} strained layer on the InAs quantum dot layer, x=0.05, the growth temperature is 500°C, and the growth thickness is 8nm;

Step 4: growing a GaAs barrier layer on the In _0.05 Ga _0.95 As strained layer, the growth temperature is 500°C, and the growth thickness is 5nm;

Step 5: growing a GaAs capping layer on the GaAs barrier layer, the growth temperature is 600° C., and the growth thickness is 40 nm.

Step 6: Repeat Step 2 to Step 5 four times on the GaAs capping layer to obtain a quintuplex array quantum dot material.

The luminescence wavelength of the obtained array quantum dot material is 1.30 μm, as shown in curve 1 in FIG. 2 . It has a five-quantum dot structure, as shown in Figure 3. The bright line in the figure shows the InAs quantum dot layer.

Embodiment 2: Each epitaxial layer is grown by MOCVD epitaxial technology, and low-toxicity Group V organic source-tert-butylarsenic (TBA) is used as the arsenic source. The preparation steps include:

Step 1: growing a GaAs transition layer on a GaAs substrate, the growth temperature is 700°C, and the growth thickness is 200nm;

Step 2: grow the InAs quantum dot layer on the GaAs transition layer in two steps. In the first step, the growth temperature is 480°C and the growth thickness is 2.4ML. The time interval between the second step and the first step is 30s. Increase the growth temperature to 500°C within a time interval, and then continue to grow at this temperature, with a growth thickness of 0.7ML;

Step 3: growing an _{InxGa1 -xAs} strained layer on the InAs quantum dot layer, x=0.09, the growth temperature is 500°C, and the growth thickness is 8nm;

Step 4: growing a GaAs barrier layer on the In _0.09 Ga _0.91 As strained layer, the growth temperature is 500°C, and the growth thickness is 5nm;

Step 5: growing a GaAs capping layer on the GaAs barrier layer, the growth temperature is 600° C., and the growth thickness is 40 nm.

Step 6: Repeat Step 2 to Step 5 four times on the GaAs capping layer to obtain a quintuplex array quantum dot material.

The luminescence wavelength of the obtained array quantum dot material is 1.31 μm, as shown in curve 2 in FIG. 2 .

Embodiment three: each epitaxial layer is grown by MOCVD epitaxial technology, and low-toxicity Group V organic source-tert-butylarsenic (TBA) is used as the arsenic source, and the preparation steps include:

Step 1: growing a GaAs transition layer on a GaAs substrate, the growth temperature is 700°C, and the growth thickness is 200nm;

Step 2: grow the InAs quantum dot layer on the GaAs transition layer in two steps. In the first step, the growth temperature is 490°C and the growth thickness is 2.2ML. The time interval between the second step and the first step is 20s. Increase the growth temperature to 500°C within a time interval, and then continue to grow at this temperature, with a growth thickness of 1.0ML;

Step 3: growing an _{InxGa1 -xAs} strained layer on the InAs quantum dot layer, x=0.12, the growth temperature is 500°C, and the growth thickness is 8nm;

Step 4: growing a GaAs barrier layer on the In _0.12 Ga _0.88 As strained layer, the growth temperature is 500°C, and the growth thickness is 5nm;

Step 5: growing a GaAs capping layer on the GaAs barrier layer, the growth temperature is 600° C., and the growth thickness is 40 nm.

Step 6: Repeat Step 2 to Step 5 four times on the GaAs capping layer to obtain a quintuplex array quantum dot material.

The luminescence wavelength of the obtained array quantum dot material is 1.33 μm, as shown in curve 3 in FIG. 2 .

Embodiment 4: Each epitaxial layer is grown by MOCVD epitaxial technology, and a low-toxic Group V organic source-tert-butylarsenic (TBA) is used as the arsenic source. The preparation steps include:

Step 1: growing a GaAs transition layer on a GaAs substrate, the growth temperature is 700°C, and the growth thickness is 200nm;

Step 2: grow the InAs quantum dot layer on the GaAs transition layer in two steps. In the first step, the growth temperature is 490°C and the growth thickness is 2.2ML. The time interval between the second step and the first step is 20s. Increase the growth temperature to 500°C within a time interval, and then continue to grow at this temperature, with a growth thickness of 1.1ML;

Step 3: growing an _{InxGa1 -xAs} strained layer on the InAs quantum dot layer, x=0.20, the growth temperature is 500°C, and the growth thickness is 8nm;

Step 4: growing a GaAs barrier layer on the In _0.20 Ga _0.80 As strained layer, the growth temperature is 500°C, and the growth thickness is 5nm;

Step 5: growing a GaAs capping layer on the GaAs barrier layer, the growth temperature is 620° C., and the growth thickness is 40 nm.

Step 6: Repeat Step 2 to Step 5 four times on the GaAs capping layer to obtain a quintuplex array quantum dot material.

The luminescence wavelength of the obtained array quantum dot material is 1.35 μm, as shown in curve 4 in FIG. 2 .

Claims (3)

1. A method for preparing InAs quantum dot materials in the 1.3 micron band, characterized in that each epitaxial layer is grown by MOCVD epitaxy; the preparation steps include: sequentially growing a GaAs transition layer, an InAs quantum dot layer, and an _InAs substrate on a GaAs substrate. Ga _1-x As strained layer, GaAs barrier layer, GaAs capping layer; InAs quantum dot layer is grown in two steps. In the first step, the growth temperature is a temperature in the range of 470-490°C, and the growth thickness is 2.0-3.0ML , the second step is separated from the first step by 20-60s in time. During this time interval, the growth temperature is increased to 490-510°C, and then the growth is continued at a temperature within this temperature range, and the growth thickness is 0.5 ~1.5ML. 2. The preparation method according to claim 1, characterized in that the InAs quantum dot layer, the _{InxGa1 -xAs} strained layer, the GaAs barrier layer, and the GaAs capping layer are repeated on the GaAs capping layer to obtain a double array The quantum dot material is repeated up to 14 times to obtain the fifteen-fold array quantum dot material. 3. The preparation method according to claim 1, characterized in that the content of the In component in the In _x Ga _1-x As strained layer is 0.05≤x≤0.02.

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